The loop PQ, as shwon in figure moves with a velocity . Both loop and velocity are in the plane of paper and a magnetic field  exists in the region  perpendicular to plane and directed inward. Find the emf induced between P and Q. 

 

• A

  B  v 2 r

• B

  B(a+ b+2r ) v

• C

  $B \left(a +b + \pi r\right) v$

• D

  $\pi r B v$